Cook potatoes in boiling water until tender; drain. Mash down and transfer to large bowl. Add half-and-half, salt, and butter. Beat with an electric mixer until light and fluffy. Fold in beaten eggs, sour cream, cottage cheese, and onions. Place in 3-quart baking dish.

In a medium bowl, mix crushed cracker crumbs with butter; sprinkle over top of potatoes. Bake, uncovered, at 350 for 30 to 35 minutes. Crumbs should be lightly browned. Makes 12 to 14 servings.